Reinforced core



June 21, 1949 M. M. MARKS 2,474,186 v REINFORCED CORE Original Filed March 20, 1944 Patented June 21, 1949 $474,186

UNITED STATES PATENT OFFICE REINFORCED CORE Milton M. Marks, Chicago, 111., assignor to Crane 00., Chicago, 111., a corporation of Illinois Substituted for application Serial No. 536,618, May 20, 1944. This application February '7, 1947, Serial No. 727,024

1 Claim. (Cl. 22-165) This application is filed in place of my abantheir dual uses as structural members and also doned patent application Serial Number 536,618, as means for forming vent passages for gases filed May 20, 1944. generated during pouring as hereinafter de- This invention relates to cores for use in molds scribed. The sand core structure 6 is shown with and is more particularly concerned with cores a pair of port openings I! and I8 through which which must be structurally reinforced due to the generated gases may be vented during pourtheir particular shapes or sizes in order that they d t is t ere ore desirable to have the remay not be readily broken before or after baking inforcing members arranged to terminate at these or while positioned in a mold during the pouring openings, as shown. of the metal. v 10 The reinforcing member l2, l3, l4 and I6 are It has heretofore been common practice to formed of material as hereinafter more specifiapply imbedded metal rods or arbors within cores cally referred to, having the physical properties for the purpose of reinforcing same, but this pracrequired to strengthen the core to permit hantice necessitates the removal of the reinforcing dling of s e t o ea e. e material members from the cast products, which is often must also be capa e of withstanding t e usual a relatively difiicult operation When the reinforccore baking temperatures without objectionable ing members are straight and even more difficult impairment of its physical properties, and furwhen such cast products are curved or have prother must be meltable and adapted for burning or jections. vaporizing at temperatures created within the It is an object of this invention to provide an vcore during the pouring of molten metal to thereimproved means and method for reinforcing by leave clean vent passages for the discharge of cores, and consists essentially in the employment gases generated within the core. It will thus be of reinforcing members formed of a material havnoted that the type of material employed must ing suitable physical properties and which will necessarily be dependent upon the phyiscal propwithstand the temperatures employed in core erties required for structural reinforcement purbaking and will subsequently melt and then burn poses, the core baking temperature, and also upon or vaporize during the casting of a product to the pouring temperature of the molten metal enthereby leave a substantially clean vent passage countered. As an example of the type of matefor the escape of gases. It will thus be noted rial which may be employed in carrying out this that reinforcing members of this type serve a invention, certain thermoplastic materials, such dual purpose, as they strengthen or reinforce the as nylon, have been found to possess the desired core sufliciently to permit handling without physical properties even after being baked within breakage and further provide vent passages for a sand core, and then melt and either burn or the escape of gases generated during and after vaporize when subjected to metal pouring temthe pouring operation. peratures to leave clean vent passages for the In the drawing: discharge of generated gases.

Fig. 1 is a plan view illustrating the application The reinforcing strength of the plastic nylon of the improved reinforcing member to a sand is employed in the core during the course of bakcore designed for use in casting a boiler section. ing and subsequently uses such property until Fig. 2 is a sectional view taken along the line the molten metal is actually being poured. At the 22 of Fig. 1. metal pouring temperature in the mold when such Referring now to the drawing for a better reinforcing of the core may be dispensed with, understanding of this invention, the sand core 6 the nylon insert melts thereby imparting to the is shown to illustrate a relatively fragile strucrelatively complex hollow casting the benefits long ture having side arms 1 and 8 and connecting end desired by industry; that is to say, there is no portions 9 and 11, all having relatively small crosslonger any Worry about core wires being left in sectional areas and therefore normally requiring the hollow casting when the core sand is being reinforcing members l2, l3, l4 and 16 in order removed. It is emphasized that the insert of to permit handling thereof without breakage. this invention is not concerned with preventing While a particular arrangement of reinforcing the deformation of the surface of the core. This members has been shown as applied to one form is taken care of in the material of which the core of core, it should be understood that this is for itself is made. Thus there is no handicap enillustrative purposes only in order to point out countered nor hardship assumed when the inmore clearly that any arrangement of reinforcsert of this invention disintegrates during the ing members within cores should contemplate normal metal pouring mold temperatures.

Nylon possesses the desirable properties in that it will not melt at core baking temperatures, say at 450 F. but in excess of such temperatures, as for example those encountered in the mold during the pouring operation at a temperature of 2500" F. the nylon will disintegrate quite readily.

Thus it'is'easy t0 see that it reinforces and supports the core'when desired toimpart to it the necessary strength for handling during the assembly of the mold and withstanding the uplifting forces on the core by the molten-metal acting underneath the core positioned in the mold during the pouring operation. "It eliminates the more serious problem heretofore-encountered of physically removing the {reinforcing inserts heretofore used, such as metalwires. for example, after the hollow casting has been made and it becomes necessary to remove the core therefrom. During a portion of the melting and subsequently during the metal cooling period this disintegration of the nylon insert serves to vent the core which-constitutes an added "advantage from the standpoint of improved foundry practice. The passage thus formed by the. disintegration of the nylon servesasa vent to exhaust the'gases'generated by'the burning. of the core binding materiaLlthelevaporation of water and other volatile materialssorgases present.

It is well known to those who areskilled in the art thattheplasticrnylon which is a generic :term

adipic acidpossesses the strength per unit weight in which the natural fibers are superior *to the metals'and is-surpassed only by flax fibers.

Another unobviousbenefit gained by this invention in employing nylon as the material for the core insert is thatit is-practically unaffected by most organic acids, alcohols, halogenated hydrocarbons, cold dilute alkalis, soaps, ketones and organic solvent mixtures. In addition from a safety or health standpoint in handling the nylon insert by the core makers it is completely inert physiologically.

It will thusi'beiseen in isummarizing ithat reinforcing members 'formedof material as hereinbefore described may readily be shaped and positioned Within sand cores during the core forming :operation to add the desired strength thereto to permit handling Without breakage, and also that ithereinforcing members melt to leave clean vent passagesof either straight or circuitous design to suit .the requirements of the core design.

I claim:

.A baked sand core of a shape requiring reinforcement, the said core having a reinforcing member imbedded therein formed of substantially rigid material consisting of a thermoplastic condensation product of the super.polyamides class and possessing physical =properties adapted to withstand core baking temperatures without disintegration but which will disintegrate at the temperatures encountered during the pouring l of molten metal into a mold employings-aidreinforced core thereby to form substantially clear, unrestricted passages through the-core for the venting of gases-'after the -molten metal has-been poured.

JREEERE'NGES iCITED The following references are of record in the ills of this patent:

UNITED STATES .PA'IENIS Number Name Date 982,670 Hanson Jan.'24, 1911 2,422,118 Meyer June'lO, 1947 OTHER REFERENCES The Foundry, June 1946, page 136. 

